<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div{
            width: 200px;
            height: 200px;
            margin: 50px auto;
            background-color: aqua;
            /* 应用画圆 宽高的一半 就是半径r*/
            border-radius: 100px;
        }
        .c{
            /* 胶囊应用 */
            width: 200px;
            height: 100px;
            background-color: blue;
            line-height: 100px;
            text-align: center;
            border-radius: 50px;
        }
    </style>
</head>
<body>
    <div></div>
    <div class="c">321</div>
</body>
</html>